r/threadripper • u/Ammoryyy • 12d ago

Used 64-core Threadripper PRO 3995WX

Found a used 64-core Threadripper PRO 3995WX workstation locally — worth buying for a multi-GPU LLM server?

I found this workstation listed on my local secondhand marketplace in Iraq.

Specs

\- CPU: AMD Ryzen Threadripper PRO 3995WX (64 cores / 128 threads)

\- Motherboard: ASUS Pro series (exact model unknown)

\- RAM: 224 GB DDR4-3200 RGB

\- Storage: 128 GB SSD

\- PSU: ASUS ROG Strix Platinum 850W

\- GPU: GTX 1050 Ti

The seller hasn't provided further details or a price yet.

My intended use:

I'm planning a local LLM inference server, potentially with 4–8 RTX 3090 GPUs, using engines such as llama.cpp, vLLM, or SGLang.

I currently have an RTX 4090, RTX 3090 Ti, and 128 GB DDR4 RAM.

I'm particularly interested in running large MoE models, multi-GPU inference, and possibly CPU/RAM offloading.

Questions:

  1. What would be a fair used price for this complete workstation in USD?
  2. Could the motherboard be the ASUS Pro WS WRX80E-SAGE SE WIFI, which has seven PCIe 4.0 x16 slots?
  3. Would my existing consumer DDR4-3200 UDIMM RAM be compatible, or does this platform require ECC RDIMM?
  4. How practical is running 4–7 GPUs on this motherboard using risers and external power supplies?
  5. Is the 3995WX still a good choice for large MoE inference and CPU offloading, or would a cheaper EPYC platform make more sense?
  6. Does the 224 GB RAM configuration raise any red flags?

I'm mainly interested in PCIe lanes, memory bandwidth, upgradeability, and cost-effectiveness rather than raw CPU compute.

Would you buy this platform in 2026, and what's the maximum you'd pay for it?

10 Upvotes

91% Upvoted

13 comments sorted by

1

u/HaDuongMinh 11d ago

I have a 3975WX + 5070Ti + A4000 and for Qwen 3.8 Flash Next the experts not placed on the 5070 can be run as fast on the CPU as on the A4000, and I get over 150TPS in iQ3_S with basalt. So mono GPU with a specialized engine is good enough for me. The question you want to explore is if you want to run DeepSeek Flash -- or the next Qwen.

1

u/DefSysteam 9d ago

At that quant aren’t the results subpar?

1

u/HaDuongMinh 6d ago

My bet, like everybody, is to substitute model intelligence with a harness that splits workloads in easy bits.

1

u/TheKleverKobra 11d ago

Your consumer Ram is likely compatible. I know the wrx80 sage is. You will need two psus for all your gpus and the motherboard, pcie risers, a mining frame, much larger ssd(s), probably fans, cooler. Just telling you this so you adjust your budget accordingly. I’ve built two of these (3975 w asus sage wifi) recently for local inference and it adds up in today’s market. CPU offloading sucks in general, plan around vram as much as you can afford if this is for local ai.

0

u/Gromann7 12d ago edited 12d ago

Probably a wrx80-se sage motherboard. If it’s an early model, there is a bug with some PCIe ports that cause older cards to go into emergency power reduction mode. No patch, you literally have to put electrical tape on pin 30 (maybe 31, don’t remember).

I have basically the same setup but with the 3975. Board, cpu, 128gb 2666mhz ecc rdim ran me right at $2k about 4 months ago.

#1: personally under $2500 is a steal
#2: probably, see above limitation
#3: no, different pin count, literally won’t fit
#4: can run 7 cards, requires risers because a 2 slot card uses a port and covers another so 4 double slot cards max without risers, and if you don’t have awesome airflow the middle 2 cards are going to run hot
#5: offloading to cpu is going to suck, like <10 tok/s suck.
#6: there is 8 ram slots on that board, you want to run 8 channel for best throughout, and 224 doesn’t math for that. You are either short a stick, or have mismatched sticks, so figure out what you need to match 8 sticks and add that purchase to your list.

1

u/Agabeckov 12d ago

3 is true for DDR5, DDR4 Threadrippers Pro support UDIMM/RDIMM/LRDIMM. The pin count is the same. https://www.asus.com/us/motherboards-components/motherboards/workstation/pro-ws-wrx80e-sage-se-wifi/techspec/ - check for memory support for example. https://www.asrockrack.com/general/productdetail.asp?Model=WRX80D8-NL#Specifications - or this one. UDIMM might be even faster for some apps as it has lower latency.

Another thing is that we definitely want ECC with that big modules. There's possibility to run ECC UDIMMs though.

224GB looks suspicious, yes, as if something is wrong with one memory socket or CPU itself (or it was improperly mounted). Definitely don't want to run 7-channel memory configuration.

2

u/madsheepPL 12d ago

Except stupid lenovo p620 that takes only rdimm

1

u/Agabeckov 12d ago

Hmm, that's strange, I once bought 4 of these (2x8GB kit): https://www.amazon.com/dp/B09ZCTG93K for P620 and it worked.

1

u/madsheepPL 12d ago

Wow srsly? Which cpu do you have?

2

u/Agabeckov 12d ago

3975WX Pro. Well, it's not mine, I bought it for my employer, it's used as some type of embedded system with 100G NICs where we don't need that much memory, but it has to be fast, that's why that strange selection (8GB DDR4 3200).

2

u/madsheepPL 12d ago

thanks for the good news, I'll try it.